Lewis, Allison

Allison Lewis was a speaker at the WEFTEC 2024 conference in New Orleans, LA October 5-9, 2024.

Titles from this speaker

Ocala Wetland Recharge Park: A Nature-Based Solution for Beneficial Reuse

Abstract

BACKGROUND Silver Springs, located in North Central Florida, is one of the state's largest first-magnitude springs and has attracted visitors since the 19th Century. World famous for its crystal-clear waters, it is the ecological and economic engine in the area. However, flow and water quality data over the past nine decades show a significant decline in spring flow and increase in nutrient concentrations which has led to the ecological degradation of the Silver Springs and Silver River systems. OBJECTIVES While not yet required by regulation, the visionary City of Ocala, located within the Silver Springs springshed, constructed a treatment wetland designed for groundwater recharge to beneficially reuse their reclaimed water by offsetting their groundwater use and nutrient loads to Silver Springs associated with municipal wastewater management. Known as the Ocala Wetland Groundwater Recharge Park, this 35-acre infiltration wetland system receives and treats up to 5 million gallons per day (mgd) of reclaimed water and stormwater to recharge the Upper Floridan Aquifer (UFA), protects water quality, and recovers and enhances the flows to Silver Springs. The Silver Springs system is subject to restrictive Total Maximum Daily Load (TMDL) regulations for nitrate and has a recovery strategy to help meet its established Minimum Flows and Levels (MFL). The Ocala Wetland Groundwater Recharge Park project supports both nitrate load reductions and recharge to help augment flows in the springshed. The Florida Department of Environmental Protection (FDEP) listed the wetland park as one of the stakeholder projects to reduce nitrogen sources in the Silver Springs Basin Management Action Plan (BMAP) area and provided Springs Funding due to its benefit to the region (FDEP, 2012 and SJRWMD, 2017). METHODOLOGY In support of the design and permitting of this project, an onsite hydrogeologic investigation, consisting of soil borings and the construction of pumping and monitoring wells across the site, was conducted to produce site-specific data. A groundwater model was then calibrated to this site-specific data and was used to evaluate the site's capacity to recharge the aquifer and the fate of the applied water to recover flows in the Silver Springs System. These efforts included innovative applications of a calibrated groundwater model combined with a wetlands treatment model to quantify recharge while ensuring the protection of water quality. It was determined that this system would have a capacity of up to 5 mgd, infiltrate an average of 5 in/day, and reduce nitrate levels to background concentrations. The designed wetland system consists of 35 acres of infiltration wetlands divided into 3 cells to receive up to 5 mgd of reclaimed and stormwater on a project area of 60 acres. The design included organically shaped cells graded in-place without the need for import of export of material to construct berms. Wetland habitat diversity was maximized by creating different ecotones across the cells that range from deep open water to shallow wetlands, islands, and rookery areas. The design also included an innovative distribution header that controls flow to each cell independently based on water level setpoints in each wetland cell. This allows for seasonal operation of water levels to maximize recharge and wetland ecological value by mimicking wetland hydroperiods that are driven by seasonal rainfall patterns. RESULTS AND CONCLUSIONS As shown in Figure 1. nitrate concentrations in the monitoring wells located within the UFA, approximately 100 feet below the wetland park, show a downward trend following park start-up and wetland planting. Nitrate concentrations in the intermediate well (within the influence of the wetland) decreased from 0.5 mg/L to 0.1 mg/L and nitrate concentrations in the compliance well decreased from approximately 1 mg/L to 0.5 mg/L after the application of reclaimed water to the site and start-up of the park. In addition, onsite recharge rates average 5 in/day, achieving the infiltration rates predicted in the groundwater model (Figure 2). The Ocala Wetland Recharge Park provides a unique case study of beneficial reuse management that addresses water supply and water quality while also giving back to the community. Since opening in the September of 2020, the park has seen over 171 bird species and an average of 3,700 visitors per month. Designed to also serve the community, the Park includes 2.5 miles of ADA-accessible trails, interactive educational displays, and some of the best birding in the County as the park was designated a Great Florida Birding and Wildlife Trail site by the Florida Wildlife Commission in 2023. The City has also developed a website and social media for the wetland park to provide the public with park photos, activities, and educational information. Further serving as an amenity to the community, the park also hosts field trips for local schools and meetings for environmental organizations like the Marion Audubon Society. In 2021, the wetland recharge park's innovation was recognized by the National Recreation and Park Association as they awarded the park with both the Innovation in Conservation Award and the 2021 Best in Innovation Award. The park represents a multi-benefit nature-based solution that should be considered for other areas in need of addressing both water supply and water quality in an innovative and natural way.

The City of Ocala, located within the Silver Springs springshed, constructed a 35-acre treatment wetland park designed to offset their groundwater use and reduce nutrient loads to Silver Springs associated with reclaimed water management. This paper will review how the 5-mgd groundwater recharge wetland treats reclaimed water and stormwater to recharge the aquifer, protects water quality, enhances flows to Silver Springs, and provides a recreational park for the community.

SpeakerLewis, Allison

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

SessionCoastal Water Management: Strategies to Eliminate Ocean Discharge

Session number611

Session locationRoom 235

TopicIntermediate Level, One Water Management, Water Reuse and Reclamation

Author(s)

Lewis, Allison, Sullivan, Gabriela, Vazquez-Burney, Rafael

Author(s)A. Lewis1, G. Sullivan2, R. Vazquez-Burney1

Author affiliation(s)1Jacobs, FL, 2City of Ocala, FL

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159511

Volume / Issue

Content sourceWEFTEC

Word count11

The Long's Park Treatment Wetlands and Park Enhancement Project

Abstract

The City of Lancaster, PA has constructed an innovative water quality improvement project in one of its public parks to capture and treat stormwater runoff as part of its Chesapeake Bay Pollutant Reduction Plan. Runoff quality improved by the project results in reduced nitrogen, phosphorus, and sediment loading to the Little Conestoga Creek in the Lower Susquehanna River Basin, which ultimately contributes to improved water quality in the Bay.

Description: The Long's Park water quality improvement project includes a pump station to convey water from Long's Pond to a constructed natural treatment system (NTS) consisting of a forebay equipped with floating wetland islands (FWI), an iron-enhanced media filter (IEMF), and two constructed marshes that discharge to Long's Pond (Figure 1). NTS are engineered ecosystems that use natural biological, physical, and chemical processes to improve water quality. With lower operating costs, less energy consumption, and fewer residuals produced than conventional active treatment, NTS provide cost-effective solutions for treatment of various types of water inflows including stormwater.

The forebay was designed as an open basin to receive the first flush of stormwater inflows and achieve significant removal of particulate solids and associated pollutants. The FWIs function to improve basin hydraulics by enhancing dispersion and by supplementing solids and nutrient removal through settling, filtering, and uptake processes associated with the suspended root mat of the aquatic plants. In addition, the FWIs are expected to provide an attractive resting, nesting, and feeding habitat for waterfowl and aquatic wildlife like frogs and turtles.

The IEMF receives the outflow from the forebay and promote phosphate removal through iron oxidation. The vertical flow filter media bed consists of pea gravel mixed with iron. Flow from the media filter passes through two constructed marshes in sequence that include deep and shallow zones for enhanced solids retention, denitrification, phosphorus uptake, and ecological habitat including mosquito control. Finally, an outflow pipe from the lower marsh was constructed to convey the outflow from the marshes to Long's Pond. To provide enhanced flushing of Long's Pond, a new pump station pumps approximately 95 liters per minute from the pond to the forebay.

Through engagement with the Long's Park Commission, public recreational use features were incorporated in the form of all-weather access trails to the NTS that wind around the site in addition to a boardwalk that enable public access through the lower marsh. Illustrative educational signs were installed to inform the public of the purpose of the project. Together, these features have created a unique and engaging experience for park visitors, who in turn have enthusiastically embraced the project.

Methodology: The Soil-Plant-Atmosphere-Water (SPAW) water balance model was used to size the Long's Park NTS based on a long-term simulation using climatic data for a 24-year period of record. This period of record was selected to represent potential climatic conditions and included a rainfall event equivalent to the 100-year, 24-hour design storm of 20 cm. The SPAW model provided a water balance for the entire NTS design and ensured the system's design capacity was sufficient for the anticipated stormwater flows.

The SPAW package includes features such as outlet pipes, outlet pumps, and runoff inflows such that a wide variety of pond situations can be described. All hydrologic processes simulated by SPAW are illustrated in Figure 2, and the processes used for the Long's Park NTS design are circled in red. The processes simulated for the NTS design and water balance model include the watershed fields/stormwater runoff, external input (from Long's Pond), evaporation, precipitation, and the outlet pipe.

Results: Through trial and adjustment of the model, the dimensions of the pond, media filter, and marshes were adjusted to ensure sufficient capacity for the design stormwater inflows. Figures 3 through 5 provide the SPAW model simulated hydroperiod for the forebay, upper marsh, and lower marsh. The NTS is projected to reduce stormwater runoff total suspended solids (TSS) and nutrients. Based on the daily water balance model conducted for this system over the 24-year period of record, the annual average inflow the NTS receives is approximately 166,558 liters per day. This total inflow includes stormwater runoff from approximately 3.1 ha of contributing drainage area and a continuous 95 liters per minute flowrate from Long's Pond. This flow was used to predict the water quality performance of the NTS.

The NTS's capacity to improve stormwater quality was evaluated using current approaches to modeling treatment wetlands. The primary removal mechanisms of NTS include solids settling, metal adsorption and precipitation, microbial transformation to gaseous compounds, and plant uptake and burial. The water quality model results indicate that in a typical year, the treatment system provides a reduction of 9 kg of phosphorus, 45kg of nitrate, and 5443 kg of TSS. As shown in Table 1, these reductions result in a 50% reduction of TP, 32% reduction of TN, and 95% reduction of TSS.

This presentation will cover lessons learned from design, construction, and maintenance, as well as qualitative and quantitative performance indicators, including initial water quality data.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

10:30:00

11:00:00

Session time

10:30:00

12:00:00

SessionInnovative Green Infrastructure Solutions in Diverse Urban Settings

Session locationMcCormick Place, Chicago, Illinois, USA

TopicStormwater

Author(s)

Wible, Daniel, Beck, Susan, Brackbill, Angela, Deger, Molly, Lewis, Allison

Author(s)D. Wible1, S. Beck1, A. Brackbill2, M. Deger2, A. Lewis1

Author affiliation(s)Jacobs1, City of Lancaster, PA2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2025

DOI10.2175/193864718825159966

Volume / Issue

Content sourceWEFTEC

Word count10

Description: The Wetlands at Long's Park: The City of Lancaster's Park Enhancement and Water...

The Wetlands at Long's Park: The City of Lancaster's Park Enhancement and Water Treatment Project

Abstract

The City of Lancaster, PA, has constructed an innovative water quality improvement project in one of its public parks to capture and treat stormwater runoff as part of its Chesapeake Bay Pollutant Reduction Plan. Runoff quality improved by the project will result in reduced nitrogen, phosphorus, and sediment loading to the Little Conestoga Creek Watershed in the Lower Susquehanna River Basin, which will ultimately contribute to improved water quality in Chesapeake Bay. The project is located in Long's Park and is designed to complement the park as an aesthetic and recreational amenity. The Park is a popular 80-acre public recreational area owned and operated by the City of Lancaster that is used extensively by residents and tourists every year. Public use features of the park include a petting zoo, pavilions, ball fields, and the 3-acre Long's Pond. Warm weather activities include music and food festivals and events, which further attract large numbers of park visitors. Because of the popularity of Long's Park, the proposed project will be highly visible and will provide a unique opportunity for public educational outreach to park visitors and surrounding municipalities, private property owners, and other engineers and professionals in the field. The Long's Park water quality improvement project includes a proposed pump station to convey water from Long's Pond to a constructed natural treatment system (NTS) consisting of a treatment train that includes a forebay equipped with floating wetland islands (FWI), an iron-enhanced sand filter (IESF), and two constructed wetland marshes, with discharge to Long's Pond. NTS are engineered or modified ecosystems that use natural biological, physical, and chemical processes to improve water quality. As an increasingly popular approach to water management, NTS are sustained by renewable natural sources of energy such as solar radiation, wind, gravity, and energy storage in biological and chemical forms. With lower operating costs, less energy consumption, and fewer residuals produced than conventional active treatment, NTS provide cost-effective solutions for treatment of various types of water inflows including stormwater. The forebay was designed as an open basin to receive the first flush of stormwater inflows and achieve significant removal of particulate solids and associated pollutants. The FWIs function to improve basin hydraulics by enhancing dispersion and by supplementing solids and nutrient removal through settling, filtering, and uptake processes associated with the suspended root mat of the aquatic plants. In addition, the FWIs are expected to provide an attractive resting, nesting, and feeding habitat for waterfowl, wading birds, and aquatic wildlife such as frogs and turtles. The IESF receives the outflow from the forebay and will promote phosphate removal through iron oxidation. The vertical flow filter media bed consists of sand mixed with iron. As stormwater infiltrates through the media bed, the elemental iron rusts to form iron oxides that bind phosphate via surface adsorption. This media bed is also expected to provide enhanced nitrification of reduced nitrogen. Flow from the sand filter passes through two constructed marshes in sequence that include deep and shallow zones for enhanced solids retention, denitrification, phosphorus uptake, and ecological habitat including natural mosquito control. The marshes are expected to polish any residual iron possible from the sand filter and stormwater via filtration of particulates, denitrification, and additional phosphorus removal. Finally, an outflow pipe from the lower marsh was constructed to convey the outflow from the marshes to Long's Pond. Long's Pond receives treated stormwater and is expected to become less eutrophic through increased flushing. To provide enhanced flushing of Long's Pond, a new pump station pumps approximately 25 gpm from Long's Pond to the forebay. Concentrations of nutrients and algal biomass are expected to decrease. The Long's Park NTS is projected to reduce stormwater runoff total suspended solids (TSS) and nutrients. Based on the daily water balance model conducted for this system over the 24-year period of record (1997-2020), the annual average inflow the NTS receives is approximately 44,000 gallons per day. This total inflow includes stormwater runoff from approximately 7.7 acres of contributing drainage area and a continuous 25 gpm flowrate from Long's Pond. This flow was used to predict the water quality performance of the Long's Park water quality improvement project. The NTS's capacity to improve stormwater quality was evaluated using current approaches to modeling treatment wetland performance. Common stormwater constituents include nutrients, suspended solids, metals, bacteria, and organic compounds. Left untreated, these pollutants can result in the eutrophication of downstream water bodies and impairment of aquatic ecosystems. NTS are documented to be an effective means of removing stormwater-derived contaminants. The primary removal mechanisms of NTS include solids settling, metal adsorption and precipitation, microbial transformation to gaseous compounds, and plant uptake and burial. The water quality model results indicate that on an annual average basis, the treatment system will provide a reduction of 20 pounds of phosphorus, 100 pounds of nitrate, and 12,000 pounds of TSS. As shown in Table 1, these reductions results in a 50% reduction of TP, 32% reduction of TN, and 95% reduction of TSS. Public recreational use features are incorporated into the concept in the form of all-weather access trails to the NTS that wind around the site in addition to a boardwalk that will enable public access through the lower marsh. The configuration of the trail is designed to allow short and long walks through the site. Educational signs will be provided in the future to inform the public of the purpose of the project. Together, these facilities are expected to create a unique and engaging experience for park visitors. This presentation will cover all aspects of this project, from its initial conceptualization to its construction, which was completed in the summer of 2023. Water quality monitoring results, if available, will also be shared.

This paper was presented at the WEF Collection Systems and Stormwater Conference, April 9-12, 2024.

SpeakerWible, Daniel

Presentation time

14:30:00

15:00:00

Session time

13:30:00

16:45:00

SessionGreen Infrastructure and Nature Based Solutions Part 2

Session number20

Session locationConnecticut Convention Center, Hartford, Connecticut

TopicCollaboration, Combined Sewer System, Coordination with Riverfront Redevelopment Efforts, Funding, Green Infrastructure, Low Impact Development, Natural Treatment Systems, Nutrient Removal, Public Education/Information/Communication, Stakeholder Engagement, Stormwater Best Management Practice, Stormwater Case Study/Application, Suspended Pavement, Water Quality, Water Resources, Wet Weather

Author(s)

Wible, Daniel

Author(s)D. Wible1, S. Beck1, A. Brackbill2, A. Lewis

Author affiliation(s)Jacobs 1; City of Lancaster, PA 2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Apr 2024

DOI10.2175/193864718825159373

Volume / Issue

Content sourceCollection Systems and Stormwater Conference

Word count16

Base text size -

Lewis, Allison

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